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O Level Biology Notes By Topics

O Level biology notes

O Levels Biology Notes - Movement of Substances

These notes will help you to review the following processes:

  • Diffusion, its role in nutrient uptake and gaseous exchange in
    plants and humans
  • Osmosis, investigate and describe its effects on plant and animal tissues
  • Active transport and its importance as an energy-consuming process by which substances are transported against a concentration gradient.

These O levels Biology notes are suitable for students in Sec 3/4 taking Pure or Combined Biology.

O Level biology notes

O Levels Biology Notes - Enzymes

These notes will help you to:

  • Explain the mode of action of enzymes in terms of an active site, enzyme-substrate complex, lowering of activation energy and enzyme specificity using the ‘lock and key’ hypothesis
  • Investigate and explain the effects of temperature and pH on the rate of enzyme catalysed reactions

These O levels Biology notes are suitable for students in Sec 3/4 taking Pure or Combined Biology.

O Level biology notes

O Levels Biology Notes - Respiration

These notes will help you to:

  • Identify parts of the lung state their functions in human gaseous exchange.
  • Describe the process of breathing.
  • Explain how the structure of an alveolus is suited for its function of gaseous exchange.
  • State the components of tobacco smoke and their effects on health.
  • Define aerobic and anaerobic respiration in human cells and state the equation, in words and symbols.
  • Explain cell respiration during intensive activities and its after effects. 

These O levels Biology notes are suitable for students in Sec 3/4 taking Pure or Combined Biology.

O Level biology notes

O Levels Biology Notes - Transport in Humans

These notes will help you:

  • Identify the main blood vessels to and from the heart, lungs, liver and kidney
  • Relate the structures of arteries, veins and capillaries to their functions.
  • Describe the transfer of materials between capillaries and tissue fluid
  • Components of blood and their roles in transport and defence:
  • List the different ABO blood groups and describe all possible combinations for the donor and recipient in blood transfusions
  • Describe the structure and function of the heart.
  • Outline the cardiac cycle during systole and diastole.
  • Describe coronary heart disease and list
    the possible causes and possible preventive measures.

These O levels Biology notes are suitable for students in Sec 3/4 taking Pure or Combined Biology subjects.

O Level biology notes

O Levels Biology Notes - Excretion in Humans

These notes will help you to:

  • Define excretion and explain the importance of removing nitrogenous and other compounds from the body
  • Identify the kidneys, ureter, bladder and urethra and their functions in
    excretion.
  • The function of the nephrons.
  • Mechanism of dialysis in the case of kidney failure

These O levels Biology notes are suitable for students in Sec 3/4 taking Pure or Combined Biology.

O Level biology notes

O Levels Biology Notes - Transport in Plants

These notes will help you to:

  • Identify the cellular and tissue structure of a dicotyledonous leaf and describe the significance of these features.
  • Identify the positions of and explain the functions of xylem vessels and phloem of a herbaceous dicotyledonous leaf and
    stem.
  • Explain how the structure of a root hair cell is suited for its function of water and ion uptake.
  • Function of Chlorophyll
  • Explain why most forms of life are completely dependent on photosynthesis

These O levels Biology notes are suitable for students in Sec 3/4 taking Pure or Combined Biology.

For more worked examples and exam resources, see our mock exam papers here.

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